This invention relates generally to apparatus enabling fluid flow and which apparatus includes a surface for providing at least in part a flow path through which a fluid flows and which apparatus is provided with structure for preventing blockage or occlusion of the flow path and for preventing the flow path from becoming blocked downstream or deadheaded. More particularly, this invention relates to a positive end expiratory pressure valve (typically referred to in the art, and hereinafter, as a PEEP valve) which includes a hollow cylinder providing a fluid flow path for exhalation gas from a patient to which the PEEP valve is connected and which hollow cylinder is provided with structure for preventing blockage or occlusion of the fluid flow path and for preventing downstream blockage or deadheading of the fluid flow path.
Numerous apparatus are known to the art which provide a fluid flow path for a fluid such as a gas. Numerous medical apparatus are known to the art which provide fluid flow paths for fluids such as oxygen, anesthesia gas, and the like, and in particular numerous medical apparatus are known to the art which provide a fluid flow path for exhalation gas from a patient's lungs such as air, oxygen, anesthesia gas, or a combination thereof.
A representative medical apparatus known to the art is the above-noted PEEP valve. Such PEEP valves, as known to the art, are used to maintain a predetermined pressure level in the lungs of a patient who is being ventilated with oxygen or anesthetized by a suitable anesthesia gas. Typically, such PEEP valve includes a spring biased relief valve which remains closed and prevents the patient from exhaling until the pressure of the patient's exhalation gas exceeds the setting of the spring biased relief valve after which the valve opens and the patient's exhalation gas is exhausted through, typically, a hollow cylinder provided on the PEEP valve which provides exit port or an internal fluid flow path for the patient's exhalation gas. As the patient is exhaling, the pressure of the exhalation gas falls until it reaches the setting of the spring biased relief valve after which the valve closes thereby preventing the further flow of exhalation gas from the patient's lungs whereupon the gas remaining in the patient's lungs which would be exhaled remains in the patient's lungs and remains in the patient's lungs at a pressure equal to, or at least substantially equal to, the pressure setting of the spring biased relief valve. As is further known to the art, it is advantageous for a patient being ventilated or anesthetized, for example, to have at least some pressure remaining in the patient's lungs and to prevent the patient's lungs from being evacuated during exhalation. The maintenance of such gas pressure in the patient's lungs is believed to have a salutary effect on the sacks or alveoli of the patient's lungs.
Referring to FIG. 1, by way of example, a patient 10 is shown being ventilated by oxygen from a suitable source not shown. oxygen, O.sub.2, enters the O.sub.2 flowmeter, flows downwardly, and is mixed with air flowing inwardly through the filter and the downward flow of the mixture of oxygen and air is accelerated by the Downs' CPAP Flowmeter shown, which functions in the nature of a Venturi tube, after which the mixture flows through the heated humidifier, through the corrugated tubing 12, through the T-piece, and into the endotracheal tube 14 with which the patient 10 is intubated. When the patient 10 exhales, the exhalation gas from the patient's lungs flows through the endotracheal tube 14, the T-piece, into the PEEP valve through which the patient's exhalation gas exits through an internal fluid flow path provided in the hollow cylinder 16 of the PEEP valve. As is known to the art with respect to PEEP valves, the exit port or fluid flow path can become inadvertently blocked or occluded such as, for example, by a portion of a pillow, sheet or blanket associated with to the patient becoming inserted, or at least partially inserted, into the exit port or fluid flow path provided by the hollow cylinder of the PEEP valve. When this occurs, the fluid flow path through the PEEP valve exit port is blocked or occluded which prevents the patient from completely exhaling causing a build up in the pressure of the gas remaining in the patient's lungs above the set PEEP valve pressure which can result in barotrauma to the patient's lungs or the production of pneumothorax in the patient's lung cavities causing lung injury.
Another example of PEEP valve usage is illustrated in FIG. 2 wherein oxygen or anesthesia gas is administered to the patient 20 through the inlet provided in the mask 22. The PEEP valve shown is mounted to the mask 22 and exhalation gas from the lungs of the patient 20 normally exits through the internal exit port provided in the hollow cylinder 24 of the PEEP valve; the exhalation gas exits through the exit port as indicated by the arrow 26. Similar to the illustration shown in FIG. 1, the exit port, or internal exhalation fluid flow path provided by the hollow cylinder 24, can become blocked or occluded by the inadvertent insertion of a portion of the patient's pillow, sheet, blanket, or other objects or materials into the PEEP valve exit port.
An illustration of downstream blockage, occlusion, or deadheading of the exit port or internal exhalation fluid flow path provided by the hollow cylinder of a PEEP valve is illustrated in FIG. 3. Unlike FIGS. 1 and 2 which illustrate open systems, FIG. 3 illustrates a closed loop system wherein there is a circular flow of gas, such as oxygen to a patient. Fresh inlet gas such as oxygen enters the system through the hose 30 as indicated by the arrow 31 and flows to the patient 36 through the corrugated tubing 37. The gas enters the T-piece 38 and flows through an endotracheal tube 40 with which the patient 36 is intubated and into the patient's lungs, not shown. Exhalation gas from the patient's lungs flows upwardly through the endotracheal tube, the T-piece 38, and the corrugated tubing 42 and through the PEEP valve shown to the expiratory dome valve shown; in particular, the exhalation gas from the patient's lungs flows through the exit port or internal fluid flow path provided by the hollow cylinder 44 of the PEEP valve to the expiratory dome valve. From the expiratory dome valve, the exhalation gas flows through a tube, not shown, into the bottom of the carbon dioxide, CO.sub.2 absorber 48 which absorbs CO.sub.2 from the patient's exhalation gas and from the absorber 48 the exhalation gas with the carbon dioxide removed is mixed with the fresh inlet gas 3 and is recirculated to the patient 36. As known to those skilled in the art, failure can result in virtually any component of the closed loop system shown in FIG. 3. For example, there could be a failure in the expiratory dome valve, or the absorber 48, and such failure could result in a downstream blockage or occlusion of the circulatory exhalation gas flow described above which could result in a downstream blockage or occlusion of such exhalation gas circulatory flow causing the flow of exhalation gas through the hollow cylinder 44 of the PEEP valve to be blocked which is typically referred to in the art as deadheaded.
Accordingly, there is a need in the art for apparatus which prevents blockage or occlusion of the above-described fluid flow paths and which prevents such fluid flow paths from being deadheaded.